Re: [HACKERS] sort on huge table

Tatsuo Ishii <t-ishii@sra.co.jp> writes:
> It worked with 2GB+ table but was much slower than before.
> Before(with 8MB sort memory): 22 minutes
> After(with 8MB sort memory): 1 hour and 5 minutes
> After(with 80MB sort memory): 42 minutes.

Oh dear.  I had tested it with smaller files and concluded that it was
no slower than before ... I guess there is some effect I'm not seeing
here.  Can you tell whether the extra time is computation or I/O (how
much does the runtime of the backend change between old and new code)?
        regards, tom lane